Mike by P. G. Wodehouse

There was just one moment, the moment in which, on going down to the junior day-room of his house to quell an unseemly disturbance, he was boisterously greeted by a vermilion bull terrier, when Mr. Downing was seized with a hideous fear lest he had lost his senses. Glaring down at the crimson animal that was pawing at his knees, he clutched at his reason for one second as a drowning man clutches at a lifebelt.

Then the happy laughter of the young onlookers reassured him.